Herbicides are commonly used to kill plants, such as weeds, exotic plants, grass, poison ivy, and other undesirable flora. Most herbicides are sprayed directly onto a selected plant in the form of a liquid chemical. The spray comes into contact with and is absorbed by tissues of the plant. The herbicide then interrupts metabolic processes of the plant, which eventually causes it to die shortly thereafter.
As many weed killers and herbicides are indiscriminate, they will kill any plant in which they come into contact with including desired vegetation. A major concern, therefore, of gardeners is to avoid inadvertently spraying herbicide onto desired vegetation surrounding the plant targeted for application of the herbicide. This may be especially difficult if desired vegetation lies underneath the targeted plant or in close proximity to the targeted plant. When desired vegetation is in close proximity to the targeted plant, it may unavoidably be within the spray path of the liquid herbicide, or can easily be contacted by the herbicide through splashing or splattering of the liquid chemical when deflected off the targeted plant.
It is also common for liquid herbicide to drip from the nozzle of a sprayer after dispensing spray when moving the sprayer from one location to another. This may cause herbicide to fall from the nozzle of the sprayer onto desired foliage. Other situations in which herbicide may contact desired vegetation occurs during windy conditions, which may cause the herbicide to drift off its intended spray path and onto desired vegetation or simply through human error (i.e., poor aim) or inaccurate sprayers as well. Accordingly, it is difficult to limit the spray path of the herbicide to the targeted plant. Often liquid herbicide comes into contact with surrounding vegetation, and as a result desired vegetation is often inadvertently killed.
One attempt to solve this problem is described in U.S. Pat. No. 6,065,244 (the '244 patent) to Randle, which shows a handheld funnel that is placed around a plant stem, and held in position while hand spraying the plant. The funnel is intended to shield surrounding vegetation from application of the herbicide spray.
One drawback associated with a handheld shielding device is the short length of the handle attached to the funnel and its close proximity to the body of the funnel. The short length of the handle forces a gardener to bend down (or kneel) to position the shield by hand around a portion of a weed, which can be awkward and tedious. Still another disadvantage of having the handle so close to the funnel is the potential for exposing the gardener's hand/arm/skin to potentially dangerous exposure to chemical spray. There is also a higher probability that being within an arm's reach of the targeted plant, the gardener will inhale toxic chemicals, especially when the liquid spray splashes off the targeted plant, the funnel itself, or there is mist associated with the sprayed chemical. Accordingly, gardener safety remains a problem with a handheld funnel device.
Another drawback associated with a conventional handheld shield device is that they have a fixed slot size which is not adjustable. This is problematic when targeting weeds with stem sizes that are thicker or much smaller than the slot of the funnel. With stems thicker than the diameter of the slot it may be difficult to position the fixed-sized funnel around the stem of such weeds. On the other hand, a fixed size slot with a diameter much larger than the stem of a weed creates a gap between the stem of the weed and the opening of the funnel. The gap provides a pathway for spray to pass through the shield and come into contact with underlying vegetation which the shield is attempting to protect.
Other attempts have been made to develop systems to control the application of liquid chemicals sprayed on selected plants. Few, if any, are readily available to gardeners in the market place as they are often inconvenient, impractical, expensive, or are not suitable for use with all types of herbicide sprayers, such as pump spray bottles.